Thermoplastic moulding materials

ABSTRACT

Thermoplastic molding compositions comprising 
     (A) 5 to 98%-wt., based on components (A) through (E), of at least one elastomeric graft copolymer, 
     (B) 1 to 90%-wt., based on components (A) through (E), of a further copolymer, 
     (C) 1 to 70%-wt., based on components (A) though (D), of an elastomeric block copolymer composed of 
     at least one block C A  (hard phase) having copolymerized units of a vinylaromatic monomer, and 
     at least one elastomeric block C (B/A)  (soft phase) having copolymerized units of a vinylaromatic monomer, and of a diene, 
     (D) 0 to 300%-wt., based on components (A) through (C), of a polycarbonate, and 
     (E) 0 to 30%-wt., based on components (A) through (E), of conventional additives and processing aids, 
     are useful for producing films, moldings or fibers.

The present invention relates to thermoplastic molding compositions withimproved processing properties, based on graft copolymers and on blockcopolymers.

Mixtures of impact-modified thermoplastic copolymers based onvinylaromatic polymers and graft rubbers are known to the skilled workeras ABS polymers or ASA polymers, and are commercially available. Blendsof these ASA polymers or ABS polymers with other thermoplastics, inparticular with polycarbonates, are also known.

The introduction of ever faster processing machinery means that productsof this type are required to have, in particular, high flowabilityduring injection molding and capability for demolding without breakage.In thermoforming a particularly important factor is high elongation atbreak.

In order to optimize these properties, use is generally made of variousadditives, but these often improve only one property while adverselyaffecting another desired property. For example, additives for improvingflowability and thermoforming properties often lead to losses ofmechanical properties, while additives for improving the moldabilityfrequently impair flowability.

U.S. Pat. No. 5,760,134 discloses thermoplastic molding compositionsmade from

(A) a graft copolymer made from an elastomeric polyacrylate graft corewith a graft shell,

(B) a thermoplastic polymer built up from styrene and/orα-methylstyrene, and, where appropriate, acrylonitrile and, whereappropriate, other monomers, and

(C) an elastomeric block copolymer built up from at least one block Aformed from vinylaromatic monomer units and forming the hard phaseand/or a block B formed from diene monomers and forming a firstelastomeric (soft) phase, and at least one elastomeric block B/A formedfrom vinylaromatic monomers and also from diene monomers and forming asoft phase.

The proportion of 1,2-linkages in the polydiene within the block B/A ofcomponent C is not disclosed in U.S. Pat. No. 5,760,134.

It is an object of the present invention, therefore, to providethermoplastic molding compositions based on ABS polymers or on ASApolymers and having a balanced property profile.

We have found that this object is achieved, in one first embodiment ofthe invention, by way of thermoplastic molding compositions comprising

(A) from 5 to 98% by weight, based on the total weight of the moldingcomposition, of an elastomeric graft copolymer built up from

(a₁) from 30 to 90% by weight, based on (A), of a graft base with aglass transition temperature (T_(g)) below −10° C. made from

(a₁₁) an at least partially crosslinked acrylate polymer formed from

(a₁₁₁) from 50 to 99.9% by weight, based on (a₁₁), of at least oneC₁-C₁₀-alkyl acrylate,

(a₁₁₂) from 0.1 to 5% by weight, based on (a₁₁), of at least onepolyfunctional crosslinking monomer and

(a₁₁₃) from 0 to 49.9% by weight, based on (a₁₁), of a further monomerwhich is copolymerizable with (a₁₁₁) selected from the group consistingof the vinyl C₁-C₈-alkyl ethers, butadiene, isoprene, styrene,acrylonitrile and methacrylonitrile, and/or methyl methacrylate

and/or

(a₁₂) a diene polymer built up from

(a₁₂₁) from 60 to 100% by weight, based on (a₁₂), of at least one dieneand

(a₁₂₂) from 0 to 40% by weight, based on (a₁₂), of furthercopolymerizable monomers selected from the group consisting of theC₁-C₁₀-alkyl acrylates, vinyl C₁-C₈-alkyl ethers, butadiene, isoprene,styrene, acrylonitrile and methacrylonitrile, and/or methylmethacrylate,

(a₂) from 10 to 70% by weight, based on (A), of a graft with a(T_(g))above 50° C., grafted onto the graft base and built up from

(a₂₁) from 50 to 95% by weight, based on (a₂), of at least onevinylaromatic monomer,

(a₂₂) from 5 to 50% by weight, based on (a₂), of at least one polar,copolymerizable comonomer selected from the group consisting ofacrylonitrile, methacrylonitrile, C₁-C₄-alkyl (meth)acrylates, maleicanhydride and maleimides, and (meth)acrylamide, and/or vinyl C₁-C₈-alkylethers, or a mixture of these,

(B) from 1 to 90% by weight, based on the total weight of the moldingcomposition, of a copolymer composed of

(b₁) from 50 to 99% by weight, based on (B), of at least onevinylaromatic monomer and

(b₂) from 1 to 50% by weight, based on (B), of monomers as described for(a₂₂),

(C) from 1 to 70% by weight, based on (A), (B), (C) and, whereappropriate, (D) and (E), of an elastomeric block copolymer composed ofat least one block C_(A) forming a hard phase and having copolymerizedunits of a vinylaromatic monomer, and

at least one elastomeric block C_((B/A)) forming a soft phase and havingcopolymerized units of a vinylaromatic monomer, and also of a diene,

where the glass transition temperature (T_(g)) of the block C_(A) isabove 25° C. and that of the block C_((B/A)) is below 25° C., and

the selected phase-volume ratio of block C_(A) to block C_((B/A)) issuch that the proportion of the hard phase in the entire block copolymeris from 1 to 40% by volume and the proportion by weight of the diene inthe entire block copolymer is less than 50% by weight,

where the proportion of 1,2-linkages in the polydiene, based on thetotal of 1,2- and 1,4-cis/trans linkages, is below 15%,

and

(D) from 0 to 300% by weight, based on the weight of components (A) to(C), of a polycarbonate,

(E) from 0 to 30% by weight, based on the total weight of the moldingcomposition, of conventional additives and processing aids.

The thermoplastic molding compositions of the invention have betterflowability than comparable molding compositions together with betterdemoldability and thermoformability and show no reduction in coatabilityand are largely free from constituents which vaporize or exude.

They are suitable for producing films, moldings (especially sheets) andfibers, with excellent capability for further processing bythermoforming, and also for producing injection moldings, especially forfast processing with short cycle times.

If (A) is a butadiene rubber they have excellent puncture resistance andmarkedly improved notch impact strength. If (A) is an acrylate rubber,very good impact strength is a particularly remarkable feature.

Many demanding applications require good processability, highflowability, good demoldability and good impact strength of the finishedpart with respect to initiated or non-initiated fracture, together withgood multiaxial impact strength (implying that the impact strength ofthe molding is good in every direction, with no directional preference),without any substantial impairment of other properties, such as heatresistance, stiffness and flexural strength.

To improve flowability it is usual to add lubricants, often with areduction in the rubber content. Products with a low rubber content flowbetter than products of the same type with high rubber content, whichhave good impact strength but poor flowability. Simultaneous improvementin impact strength and flowability cannot be obtained simply by changingthe rubber content.

A further object of the present invention is therefore to providethermoplastic molding compositions based on ABS polymers or on ASApolymers, in particular on ABS polymers, with better flowability andimpact strength than those of conventional materials and moreover withbetter demoldability, together with paler intrinsic color.

We have found that this object is achieved by way of another embodimentof the present invention. This embodiment provides thermoplastic moldingcompositions comprising

(A) from 5 to 98.9% by weight, based on the total weight of the moldingcomposition, of an elastomeric graft copolymer built up from

(a₁) from 30 to 90% by weight, based on (A), of a graft base with aglass transition temperature (T_(g)) below −10° C. made from

(a₁₁) an at least partially crosslinked acrylate polymer formed from

(a₁₁₁) from 50 to 99.9% by weight, based on (a₁₁), of at least oneC₁-C₁₀-alkyl acrylate,

(a₁₁₂) from 0.1 to 5% by weight, based on (a₁₁), of at least onepolyfunctional crosslinking monomer and

(a₁₁₃) from 0 to 49.9% by weight, based on (a₁₁), of at least onefurther monomer which is copolymerizable with (a₁₁₁) selected from thegroup consisting of the vinyl C₁-C₈-alkyl ethers, butadiene, isoprene,styrene, acrylonitrile and methacrylonitrile, and/or methyl methacrylate

and/or

(a₁₂) a diene polymer built up from

(a₁₂₁) from 60 to 100% by weight, based on (a₁₂), of at least one dieneand

(a₁₂₂) from 0 to 40% by weight, based on (a₁₂), of furthercopolymerizable monomers selected from the group consisting of theC₁-C₁₀-alkyl acrylates, C₁-C₈-alkyl vinyl ethers, butadiene, isoprene,styrene, acrylonitrile and methacrylonitrile, and/or methylmethacrylate,

(a₂) from 10 to 70% by weight, based on (A), of a graft with a glasstransition temperature (T_(g)) above 50° C., grafted onto the graft baseand built up from

(a₂₁) from 65 to 95% by weight, based on (a₂), of at least onevinylaromatic monomer,

(a₂₂) from 5 to 35% by weight, based on (a₂), of at least one polar,copolymerizable comonomer selected from the group consisting ofacrylonitrile, methacrylonitrile, C₁-C₄-alkyl (meth)acrylates, maleicanhydride and maleimides, and (meth)acrylamide, and/or vinyl C₁-C₈-alkylethers, or a mixture of these,

(B) from 1 to 90% by weight, based on the total weight of the moldingcomposition, of a copolymer composed of

(b₁) from 69 to 81% by weight, based on (B), of at least onevinylaromatic monomer

and

(b₂) from 19 to 31% by weight, based on (B), of monomers as describedfor (a₂₂),

(C) from 1 to 70% by weight, based on (A), (B), (C) and, whereappropriate, (D) and (E), of an elastomeric block copolymer composed of

at least one block C_(A) forming a hard phase and having copolymerizedunits of a vinylaromatic monomer, and

at least one elastomeric block C_((B/A)) forming a soft phase and havingcopolymerized units of a vinylaromatic monomer, and also of a diene,

where the glass transition temperature (T_(g)) of the block C_(A) isabove 25° C. and that of the block C_((B/A)) is below 25° C., and

the selected phase-volume ratio of block C_(A) to block C_((B/A)) issuch that the proportion of the hard phase in the entire block copolymeris from 1 to 40% by volume and the proportion by weight of the diene inthe entire block copolymer is less than 50% by weight,

where the proportion of 1,2-linkages in the polydiene, based on thetotal of 1,2- and 1,4-cis/trans linkages, is below 15%,

and

(D) from 0 to 300% by weight, based on the weight of components (A) to(C), of a polycarbonate, of S-MA copolymers (styrene-maleic anhydridecopolymers), of S-imide-MA copolymers (styrene-imide-maleic anhydridecopolymers), of S-imide-AN-MA copolymers(styrene-imide-acrylonitrile-maleic anhydride copolymers), of apolymethacrylimide, or of a polymethacrylate, and

(E) from 0 to 30% by weight, based on the total weight of the moldingcomposition, of conventional additives and processing aids.

In this embodiment it is preferable to use a diene polymer (a₁₂) asgraft base (a₁). It is particularly preferable to use a butadienepolymer, and it is very particularly preferable for a butadiene polymerto be used and for the proportion of component C to be from 0.1 to 15%by weight, based on (A), (B), (C) and, where appropriate, (D) and (E).

The flowability and the impact strength of the molding compositions ofthe invention, in particular of those based-on ABS, i.e. those in whicha diene polymer (a₁₂) is used as graft base (a₁) can be significantlyimproved even with small amounts of component C. This is particularlythe case if the content of component (b₂) in the copolymer (B) used isin the range from 19 to 31% by weight, based on component (B).

Besides improved flowability and impact strength with respect toinitiated and to non-initiated fracture, even at small proportions ofcomponent C, good demoldability is achieved with very pale intrinsiccolor. On extrusion to give sheets, the molding compositions of thisembodiment of the invention have a substantial improvement in impactstrength perpendicular to the extrusion direction as a result ofaddition of component (C).

The molding compositions of this embodiment of the invention aretherefore particularly suitable for producing moldings, sheets,profiles, pipes and fibers, which can give excellent results in furtherprocessing via thermoforming, and also for producing injection-moldedparts, in particular where there is fast processing with short cycletimes and where there are high requirements placed upon the mechanicalproperties of the finished part.

In the first embodiment, component (A) of the molding compositions ofthe invention comprises from 5 to 98% by weight, preferably from 10 to90% by weight, and in particular from 15 to 80% by weight, based on thetotal weight of the molding compositions, of an elastomeric graftcopolymer.

In the second embodiment, component (A) of the molding compositions ofthe invention comprises from 5 to 98.9% by weight, preferably from 5 to98% by weight, and in particular from 10 to 90% by weight, and veryparticularly preferably from 15 to 80% by weight, based on the totalweight of the molding compositions, of at least one elastomeric graftcopolymer.

This graft copolymer (A) has been built up from a graft base (a₁) with aglass transition temperature T_(g) below −10° C. and from a graft (a₂)with a glass transition temperature T_(g) above 50° C., the quantitativeproportion of the graft base (a₁₁)+(a₁₂) being from 30 to 90% by weight,preferably from 35 to 85% by weight, and in particular from 40 to 80% byweight, and the graft (a₂) correspondingly making up from 10 to 70% byweight, preferably from 15 to 65% by weight, and in particular from 20to 60% by weight.

The structure of the graft copolymer (A) is described in more detailbelow.

The graft base (a₁) has been built up from

(a₁₁) an at least partially crosslinked acrylate polymer formed from

(a₁₁₁) from 50 to 99.9% by weight, based on (a₁₁), of at least oneC₁-C₁₀-alkyl acrylate,

(a₁₁₂) from 0.1 to 5% by weight, based on (a₁₁), of at least onepolyfunctional crosslinking monomer and

(a₁₁₃) from 0 to 49.9% by weight, based on (a₁₁), of at least onefurther monomer which is copolymerizable with (a₁₁₁) selected from thegroup consisting of the vinyl C₁-C₈-alkyl ethers, butadiene, isoprene,styrene, acrylonitrile and methacrylonitrile, and/or methyl methacrylate

and/or

(a₁₂) a diene polymer built up from

(a₁₂₁) from 60 to 100% by weight, based on (a₁₂), of one or more dienesand

(a₁₂₂) from 0 to 40% by weight, based on (a₁₂), of other copolymerizablemonomers selected from the group consisting of the vinyl C₁-C₈-alkylethers, C₁-C₁₀-alkyl acrylates, isoprene, styrene, acrylonitrile andmethacrylonitrile, and/or methyl methacrylate.

Molding compositions which may be used are therefore those in which thegraft base present in component (A) is either an acrylate polymer (a₁₁)alone or a butadiene polymer (a₁₂) alone or a mixture of two polymers(a₁₁) and (a₁₂).

In cases where mixtures made from the polymers (a₁₁) and (a₁₂) are used,the mixing ratio is not critical but is generally in the range from 4:1to 1:4, in particular from 1:2 to 2:1.

Preference is given to those thermoplastic molding compositions in whicha graft copolymer with a graft base (a₁₂) (diene polymer, in particularbutadiene polymer) is used as component (A).

The acrylate polymers (a₁₁) have been built up from

(a₁₁₁) from 50 to 99.9% by weight, preferably from 55 to 98% by weight,and in particular from 60 to 90% by weight, based on (a₁₁), of at leastone C₁-C₁₀-alkyl acrylate. Preferred acrylates are C₂-C₁₀-alkylacrylates, in particular ethyl acrylate, tert-butyl acrylate, isobutylacrylate, n-butyl acrylate and 2-ethylhexyl acrylate, the twolast-mentioned being particularly preferred.

(a₁₁₂) from 0.1 to 5% by weight, preferably from 0.25 to 4% by weight,and in particular from 0.5 to 3% by weight, based on (a₁₁), ofcrosslinking monomers, for example polyfunctional monomers having atleast 2 non-conjugated olefinic double bonds, examples which should bespecifically mentioned being ethylene glycol diacrylate, butanedioldiacrylate, hexanediol diacrylate, ethylene glycol dimethacrylate,butanediol dimethacrylate, hexanediol dimethacrylate, divinylbenzene,diallyl maleate, diallyl fumarate, diallyl phthalate, triallylcyanurate, triallyl isocyanurate, tricyclodecenyl acrylate,dihydrodicyclopentadienyl acrylate, triallyl phosphate, allyl acrylate,allyl methacrylate and dicyclopentadienyl acrylate (DCPA) (cf. DE-C 1260 135).

(a₁₁₃) from 0 to 49.9% by weight, preferably from 5 to 44.9% by weight,and in particular from 10 to 39.9% by weight, based on (a₁₁), ofmonomers copolymerizable with (a₁₁₁) selected from the group consistingof vinyl C₁-C₈-alkyl ethers (e.g. vinyl methyl ether, vinyl propylether, vinyl ethyl ether), butadiene, isoprene, styrene, acrylonitrileand methacrylonitrile, and/or methyl methacrylate.

The use of comonomers of this type can control the property profile ofthe polymers (a₁₁), e.g. with respect to degree of crosslinking, and inmany cases this can be desirable.

Processes for preparing polymers (a₁₁) are known to the skilled workerand are described in the literature. Products of this type are alsoavailable commercially.

A preparation process which has proven particularly advantageous in somecases is emulsion polymerization, as described in DE-C 12 60 135.

In the preparation of the graft copolymer (A) by the method described inDE-C-12 60 135, the graft base (a₁) is first prepared. If the graft baseis to be an acrylate rubber, one or more acrylate(s) (a₁₁₁), apolyfunctional monomer (a₁₁₂) and, if used, another copolymerizedmonomer (a₁₁₃) are polymerized in aqueous emulsion at from 20 to 100°C., preferably from 50 to 80° C.

The usual emulsifiers, such as the alkali metal salts of alkyl- andalkylarylsulfonic acids, alkyl sulfates, fatty alcohol sulfonates, saltsof higher fatty acids having from 10 to 30 carbon atoms, or resin soaps,may be used. Preference is given to the sodium or potassium salts ofalkylsulfonic acids or of fatty acids having from 10 to 18 carbon atoms.It is advantageous to employ the emulsifiers in an amount of from 0.5 to5% by weight, in particular from 0.5 to 2% by weight, based on the totalweight of the monomers used for the preparation of the graft base (a₁).A water/monomer ratio of from 2:1 to 0.7:1 is generally used.

Polymerization initiators used are in particular the customarypersulfates, e.g. potassium peroxodisulfate, but redox systems are alsosuitable. The amount of initiators (e.g. from 0.1 to 1% by weight, basedon the total weight of the monomers) depends, in a known manner, on thedesired molecular weight.

Polymerization auxiliaries which may be used are the usual buffersubstances capable of setting a pH of preferably from 6 to 9, e.g.sodium bicarbonate and sodium pyrophosphate, and from 0.1 to 3% byweight of a molecular weight regulator, such as a mercaptan, terpinol ordimeric α-methylstyrene.

The precise polymerization conditions, in particular the type, manner ofaddition and amount of emulsifier, are determined within the rangesgiven above so that the resultant latex of the crosslinked acrylatepolymer (a₁₁) has a d₅₀ in the range from about 30 to 1000 nm,preferably from 50 to 900 nm.

The d₅₀ of the particle size is defined in the usual way as the ponderalmedian of the particle size as determined with an analyticalultracentrifuge by the method of W. Scholtan and H. Lange, Kolloid-Z.and Z.-Polymere 250 (1972) pp. 782-796. The ultracentrifuge measurementgives the integral mass distribution of the particle diameter of aspecimen. From this it is possible to deduce what percentage by weightof the particles have a diameter which is the same as or less than aparticular size. The median particle diameter, also termed d₅₀ of theintegral mass distribution, is defined as the value at which 50% byweight of the particles have a smaller, and 50% by weight of theparticles a larger, diameter than the d₅₀.

In place of the acrylate polymers (a₁₁), the graft copolymers (A) canalso comprise diene polymers (a₁₂) as graft base. The polymers (a₁₂) arediene copolymers which besides from 60 to 100% by weight, preferablyfrom 70 to 99% by weight, of one or more dienes, preferably butadiene orisoprene, can also comprise up to 40% by weight, preferably from 2 to30% by weight, of further copolymerizable monomers, suitable examples ofwhich are both the alkyl acrylates described above under (a₁₁₁) and themonomers (a₁₁₃) copolymerizable with (a₁₁₁); for further details,reference may be made to the description at those points.

If the graft core (a₁) is to be a diene polymer, a useful procedure isas follows: the elastomer, the graft base (a₁₂), is prepared bypolymerizing components (a₁₂₁) and (a₁₂₂) in aqueous emulsion in amanner known per se at from 20 to 100° C., preferably from 50 to 90° C.

Use may be made of the usual emulsifiers, polymerization initiators andother polymerization auxiliaries described above for preparation ofacrylate polymer (a₁₁), for example buffers and molecular weightregulators, in the amounts mentioned at that juncture.

The specific polymerization conditions selected within theabovementioned ranges for preparing the diene polymer (a₁₂), inparticular the type, manner of metering, and amount of the emulsifier,are such that the resultant latex of the diene polymer (a₁₂) has a d₅₀value (cf. above) in the range from about 50 to 750 nm, preferably inthe range from 70 to 600 nm. As an alternative, it is also possible toagglomerate an emulsion polymer with a median particle size in the rangefrom 60 to 150 nm, as described in DE-A 24 279 60, for example.

A graft (a₂) is grafted onto the graft base (a₁₁) and/or (a₁₂), and isobtained by copolymerizing

(a₂₁) from 50 to 95% by weight, preferably from 60 to 90% by weight, inparticular from 62 to 85% by weight, based on (a₂), of a vinylaromaticmonomer, preferably styrene or substituted styrenes of the formula I

where R is C₁-C₈-alkyl, hydrogen or halogen and R¹ is C₁-C₈-alkyl orhalogen and n is 0, 1, 2 or 3, preferably styrene, α-methylstyrene,p-methylstyrene or tert-butylstyrene, and

(a₂₂) from 5 to 50% by weight, preferably from 10 to 40% by weight, andin particular from 15 to 38% by weight, based on (a₂), of a polarcopolymerizable monomer selected from the group consisting ofacrylonitrile, methacrylonitrile, C₁-C₄-alkyl (meth)acrylates, maleicanhydride and maleimides, (meth)acrylamide and/or vinyl C₁-C₈-alkylethers or mixtures of these.

In the second embodiment of the invention, the proportion of components(a₂₁) and (a₂₂) in the graft (a₂) is:

(a₂₁) from 65 to 95% by weight, preferably from 67 to 90% by weight, andin particular from 70 to 85% by weight, based on (a₂), of anabovementioned vinylaromatic monomer, and

(a₂₂) from 5 to 35% by weight, preferably from 10 to 33% by weight, andin particular from 15 to 30% by weight, based on (a₂), of anabovementioned polar copolymerizable monomer.

The graft shell (a₂) may be prepared in one or more steps, e.g. in twoor three steps, without any resultant effect on its overall makeup.

The graft shell is preferably prepared in emulsion, as described in DE-C1 260 135, DE-A 32 27 555, DE-A 31 49 357, DE-A 31 49 358 and DE-A 34 14118, for example.

Depending on the conditions selected, there may be a certain proportionof free copolymers of styrene and acrylonitrile formed in the graftcopolymerization.

It is again advantageous to carry out the graft copolymerization ontothe polymer which serves as graft base (a₁) in aqueous emulsion. It maybe undertaken in the same system used for polymerization of the graftbase, further emulsifier and initiator being added if required. Theseneed not be identical with the emulsifiers and initiators used forpreparing the graft base (a₁). For example it can be expedient to use apersulfate as initiator for preparing the graft base (a₁) but to employa redox initiator system for polymerizing the graft shell (a₂).Otherwise, the factors relevant to selection of emulsifier, initiatorand polymerization auxiliaries are those given for the preparation ofthe graft base (a₁).

The monomer mixture to be grafted can be added to the reaction mixtureall at once, batchwise in several steps or preferably continuouslyduring the polymerization. The graft copolymerization is advantageouslycontrolled in such a manner that the resulting degree of grafting isfrom 10 to 60% by weight, preferably from 15 to 55% by weight.

The graft copolymer (A) ((a₁)+(a₂)) generally has a median particle sizeof preferably from 30 to 1000 nm, in particular from 100 to 900 nm (d₅₀ponderal median). The conditions for preparing the elastomer (a₁) andfor grafting are therefore preferably selected so as to give particlesizes in this range. Measures for this are known and are described, forexample, in DE-C-1 260 135 and DE-A 28 26 925 and in Journal of AppliedPolymer Science, Vol. 9 (1965), pp. 2929-2938. The particle sizeincrease in the elastomer latex can be achieved, for example, by meansof agglomeration.

In some cases, mixtures of several acrylate polymers having differentparticle sizes have also proven successful. Products of this type aredescribed in DE-A 28 26 925 and U.S. Pat. No. 5,196,480, to whichreference may be made at this point for further details.

Preferred mixtures of acrylate polymers are therefore those in which afirst polymer has a particle size d₅₀ in the range from 50 to 150 nm anda second polymer has a particle size of from 200 to 700 nm, as describedin the U.S. Pat. No. 5,196,480 mentioned above.

Preference is also given to the use of mixtures of polymers (a₁₁) (asdescribed in DE-A 11 64 080, DE-PS 19 11 882 and DE-A 31 49 358) andpolymers (a₁₂), where the polymers (a₁₂) generally have a medianparticle size in the range from 30 to 1000 nm, preferably from 100 to900 nm.

As component (B), the molding compositions of the invention comprisefrom 1 to 90% by weight, preferably from 5 to 85% by weight,particularly preferably from 10 to 80% by weight, based on the totalweight of the molding composition, of a copolymer made from

(b₁) from 50 to 99% by weight, preferably from 55 to 90% by weight, andin particular from 65 to 85% by weight, based on (B), of vinylaromaticmonomers, preferably styrene and/or substituted styrenes of the formulaI

and

(b₂) from 1 to 50% by weight, preferably from 10 to 45% by weight, andin particular from 15 to 35% by weight, based on (B), of the monomersdescribed for (a₂₂).

In the second embodiment of the invention, the proportion of components(b₁) and (b₂) in component (B) is:

(b₁) from 69 to 81% by weight, preferably from 70 to 78% by weight, andin particular from 70 to 77% by weight, based on (B), of theabovementioned vinylaromatic monomers, and

(b₂) from 19 to 31% by weight, preferably from 22 to 30% by weight,particularly preferably from 23 to 30% by weight, based on (B), of themonomers described for (a₂₂), acrylonitrile being particularlypreferably used as component (b₂).

Products of this type may be prepared by the processes described in DE-A10 01 001 and DE-A 10 03 436, for example. Copolymers of this type arealso available commercially. The average molecular weight determined bylight scattering is preferably in the range from 40,000 to 500,000, inparticular from 100,000 to 250,000, corresponding to viscosity numbersin the range from 40 to 200 ml/g, preferably from 40 to 160 ml/g(measured on a 0.5% strength by weight solution in dimethylformamide at25° C.).

The polymer (B) may also be a mixture of various copolymers of styreneor, respectively, α-methylstyrene and acrylonitrile, for examplediffering in their acrylonitrile content or average molecular weight.

Based on the entirety of components (A), (B), (C) and, whereappropriate, (D) and (E) the proportion of component (C) in the moldingcompositions is from 1 to 70% by weight, preferably from 1 to 50% byweight, and particularly preferably from 1 to 40% by weight.

In the second embodiment of the invention, the proportion of component(C) in the molding compositions, based on the entirety of components(A), (B), (C) and, where appropriate, (D) and (E) is from 0.1 to 70% byweight, preferably from 0.1 to 50% by weight, and particularlypreferably from 0.1 to 40% by weight. The proportion of component (C) isvery particularly preferably from 0.1 to 15% by weight, in particularfrom 0.5 to 15% by weight and very particularly from 1 to 15% by weight.

Component (C) is an elastomeric block copolymer made from

at least one block C_(A) forming a hard phase and having copolymerizedunits of a vinylaromatic monomer, and

at least one elastomeric block C_((B/A)) forming a soft phase and havingunits of a vinylaromatic monomer, and also of a diene,

where the glass transition temperature (T_(g)) of the block C_(A) isabove 25° C., preferably above 50° C., and that of the block C_((B/A))is below 25° C., preferably below 50° C., and

the selected phase-volume ratio of block C_(A) to block C_((B/A)) issuch that the proportion of the hard phase in the entire block copolymeris from 1 to 40% by volume and the proportion by weight of the diene isless than 50% by weight,

where the proportion of 1,2-linkages in the polydiene, based on thetotal of 1,2- and 1,4-cis/trans linkages, is below 15%, preferably below12%.

Detailed information on the structure and preparation of component C hasbeen disclosed in DE-A 19 615 533, which is incorporated here by way ofreference.

Preferred vinylaromatic compounds are styrene and also α-methylstyrene,1,1-diphenylethylene and vinyltoluene, and also mixtures of thesecompounds. Preferred dienes are butadiene and isoprene, and alsopiperylene, 1-phenylbutadiene, and also mixtures of these compounds.

A particularly preferred monomer combination is butadiene and styrene.

All of the weight and volume data below are based on this combination.If the industrial equivalents of styrene and butadiene are used, thedata has to be converted appropriately where necessary.

An example of the structure of the C_((B/A)) block is from 75 to 30% byweight of styrene and from 25 to 70% by weight of butadiene. It isparticularly preferable for a soft block to have a portion of from 35 to70% of butadiene and a proportion of from 65 to 30% of styrene.

For the monomer combination styrene/butadiene, the proportion of thediene by weight in the entire block copolymer is from 15 to 65% byweight, and that of the vinylaromatic component is correspondingly from85 to 35% by weight. Particular preference is given to butadiene-styreneblock copolymers having a monomer makeup of from 25 to 60% by weight ofdiene and from 75 to 40% by weight of vinylaromatic compound.

Examples of a block copolymer C are any of the formulae 1 to 11:

 (C_(A)-C_((B/A)))_(n)  (1)

(CA-C_((B/A)))_(n)-C_(A)  (2)

C_((B/A))-(CA-C_((B/A)))_(n)  (3)

X-[(C_(A)-C_((B/A)))_(n)]_(m+1)  (4)

X-[(C_((B/A))-C_(A))_(n)]_(m+1)  (5)

X-[(C_(A)-C_((B/A)))_(n)-C_(A)]_(m+1)  (6)

X-[(C_((B/A))-C_(A))_(n)-C_((B/A))]_(m+1)  (7)

Y-[(C_(A)-C_((B/A)))_(n)]_(m+1)  (8)

Y-[(C_((B/A))-C_(A))_(n)]_(m+1)  (9)

Y-[(C_(A)-C_((B/A)))_(n)-C_(A)]_(m+1)  (10)

Y-[(C_((B/A))-CA))_(n)-C_((B/A))]_(m+1)  (11)

where C_(A) is the vinylaromatic block and C_((B/A)) is the soft phase,i.e. the block built up randomly from diene units and from vinylaromaticunits, X is the residue of an n-functional initiator, Y is the residueof an m-functional coupling agent, and m and n are natural numbers from1 to 10.

Preference is given to block copolymers of one of the formulaeC_(A)-C_((B/A))-C_(A), X-[-C_((B/A))-C_(A)]₂ and Y-[-C_((B/A))-C_(A)]₂(the meaning of the abbreviations being as above), and particularpreference is given to a block copolymer whose soft phase subdividesinto the following blocks

C_((B/A)1)-C_((B/A)2)  (12)

C_((B/A)1)-C_((B/A)2)-C_((B/A)1)  (13)

C_((B/A)1)-C_((B/A)2)-C_((B/A)3)  (14)

where the blocks have different structures and/or thevinylaromatic/diene ratio in the individual blocks C_((B/A)) changes insuch a way that there is a gradient of makeupC_((B/A)p1)<<C_((B/A)p2)<<C_((B/A)p3) . . . in each subsection(sub-block), the glass transition temperature T_(g) of each sub-blockbeing below 25° C. Block copolymers of this type, which within oneblock. C_((B/A)) have, for example, p repeating sections (sub-blocks)whose monomer build-up varies can be formed by adding the monomers in pportions, p being an integer from 2 to 10. Addition in portions can beuseful for controlling the heat flux within the reaction mixture, forexample.

Preference is also given to a block copolymer each of whose moleculeshas two or more blocks C_((B/A)) and/or C_(A), each of differentmolecular weight.

It is also possible for a block C_(B) to take the place of a block C_(A)built up exclusively from vinylaromatic units, since the essential pointis solely that an elastomeric block copolymer is formed. Examples ofstructures of copolymers of this type are (15) to (18)

C_(B)-C_((B/A))  (15)

C_((B/A))-C_(B)-C_((B/A))  (16)

C_((B/A)1)-C_(B)-C_((B/A)2)  (17)

C_(B)[C_((B/A)1)-C_((B/A)2)]  (18)

The block polymers are prepared by anionic polymerization in a non-polarsolvent, with initiation by organometallic compounds. Preference isgiven to compounds of the alkali metals, particularly of lithium.Examples of initiators are methyllithium, ethyllithium, propyllithium,n-butyllithium, sec-butyllithium and tert-butyllithium. Theorganometallic compound is in the form of a solution in a chemicallyinert hydrocarbon when added. The amount added depends on the desiredmolecular weight of the polymer, but is generally from 0.002 to 5 mol %,based on the monomers. Preferred solvents used are aliphatichydrocarbons such as cyclohexane or methylcyclohexane.

Within the block copolymer, the random blocks which contain bothvinylaromatic and diene are prepared with addition of a solublepotassium salt, in particular of a potassium alkoxide.

It is likely here that the potassium salt enters into metal exchangewith the lithium-carbanion ion pair, giving potassium carbanions, whichpreferentially form adducts with styrene, whereas lithium carbanionspreferentially form adducts with butadiene. Since potassium carbanionsare significantly more reactive, even a small fraction, specificallyfrom {fraction (1/10)} to {fraction (1/40)}, is probably sufficienttogether with the predominant lithium carbanions to render the averageincorporation of styrene the same as that of butadiene. It is alsopossible that during the polymerization procedure there is frequentmetal exchange between the living chains, and also between living chainsand the dissolved salt, so that the same chain forms an adductpreferentially with styrene on one particular occasion, and subsequentlyin turn with butadiene. The result is then that the copolymerizationparameters for styrene and butadiene are approximately identical.

Particularly suitable potassium salts are potassium alkoxides, and inparticular here tertiary alkoxides having at least 7 carbon atoms.Examples of typical alcohols corresponding to these are3-ethyl-3-pentanol and 2,3-dimethyl-3-pentanol. Tetrahydrolinalool(3,7-dimethyl-3-octanol) has proven particularly suitable. Besides thepotassium alkoxides, other potassium salts which are inert to alkylmetal compounds are also suitable in principle. Mention should be madehere of potassium dialkylamides, alkylated potassium diarylamides,alkylthiolates and alkylated arylthiolates.

The juncture at which the potassium salt is added to the reaction mediumis important. The monomer for the first block and at least some of thesolvent are usually present in the initial charge in the reactionvessel. It is not advisable to add the potassium salt at this juncture,since traces of protic contaminants hydrolyze at least some of the saltto give KOH and alcohol, and the potassium ions have then beenirreversibly deactivated for the polymerization. The lithium organylcompound should therefore be added first and mixed in, and only then thepotassium salt. If the first block is a homopolymer, it is advisable notto add the potassium salt till shortly prior to polymerizing the randomblock.

The potassium alkoxide may readily be prepared from the correspondingalcohol by stirring a cyclohexane solution in the presence of excesssodium/potassium alloy. After 24 hours at 25° C. evolution of hydrogenhas ended, and with this the reaction. However, the reaction time mayalso be reduced by refluxing at 80° C. for a few hours. A possiblealternative reaction involves mixing the alcohol with a small excess ofpotassium methoxide, potassium ethoxide or potassium tert-butoxide inthe presence of a high-boiling inert solvent, such as decalin orethylbenzene, distilling off the low-boiling alcohol, in this casemethanol, ethanol or tert-butanol, diluting the residue withcyclohexane, and filtering off to remove excess low-solubility alkoxide.

Addition of the potassium compound usually achieves a proportion of from11 to 9% of 1,2-linkages, based on the total of 1,2- and 1,4-linkages inthe diene. In contrast, when a Lewis base is used according to DE-A 4420 952 the values achieved for the proportion of 1,2- and, respectively,1,4-linkages in the diene units are from 15 to 40% for the 1,2-linkagesand from 85-60% for the 1,4-linkages, for example, based in each case onthe total amount of copolymerized diene units.

The polymerization temperature may be from 0 to 130° C., preferably from30 to 100° C.

The proportion of the soft phase built up from diene sequences and fromvinylaromatic sequences is from 60 to 95% by volume, preferably from 70to 90% by volume and particularly preferably from 80 to 90% by volume.The blocks C_(A) produced from the vinylaromatic monomers form the hardphase, the proportion of which by volume is correspondingly from 5 to40%, preferably from 10 to 30% and particularly preferably from 10 to20%.

It should be pointed out that because each of the numeric values hasbeen rounded there is no precise agreement between the abovementionedquantity ratios of vinylaromatic compound and diene, the thresholdvalues of the phase volumes stated above and the makeup implied by theglass transition temperature ranges according to the invention. If thiswere the case it would be merely coincidental.

The proportion of the two phases by volume can be measured byphase-contrast electron microscopy or solid-state NMR spectroscopy.After osmium degradation of the polydiene fraction, the proportion ofthe vinylaromatic blocks can be determined by precipitation andweighing. If polymerization is always allowed to proceed to completion,the future phase ratio of a polymer can be calculated from the amountsof monomers employed.

For the purposes of the invention, the block copolymers areunambiguously defined by the quotient calculated from the proportion byvolume in percent of the soft phase formed by the C_((B/A)) blocks andthe proportion of diene units in the soft phase, which for thecombination styrene/butadiene is from 25 to 70% by weight.

The glass transition temperature (T_(g)) is influenced by the randomincorporation of the vinylaromatic compounds into the soft block of theblock copolymer and by the use of potassium alkoxides during thepolymerization.

The glass transition temperature is typically from −50 to +25° C.,preferably from −50 to +5° C. The glass transition temperature of thepotassium-catalyzed random copolymers of the invention is on averagelower by from 2 to 5° C. than in the case for the correspondingLewis-base-catalyzed products, since the latter have an increasedproportion of butadiene 1,2-linkages. The glass transition temperatureof 1,2-polybutadiene is higher by about 70-90° C. than that of1,4-polybutadiene. The molar mass of the block C_(A) here is generallyfrom 1000 to 200000, preferably from 3000 to 80000 [g/mol]. C_(A) blockswithin one molecule may have different molar masses.

The molar mass of the block C_((B/A)) is usually from 2000 to 250000[g/mol], preferred values being from 5000 to 150000 [g/mol].

Like the blocks C_(A), blocks C_((B/A)) may assume different molar massvalues within one molecule.

The coupling center X is formed by reaction of the living anionic chainends with an at least bifunctional coupling agent. Examples of suchcompounds are found in U.S. Pat. No. 3,985,830, 3,280,084, 3,637,554 and4,091 053. Preference is given to the use of, for example, epoxidizedglycerides, such as epoxidized linseed oil or soybean oil;divinylbenzene is also suitable. Dichlorodialkylsilanes, dialdehydes,such as terephthalaldehyde, and esters, such as ethyl formate orbenzoate, are suitable specifically for dimerization.

Preferred polymer structures are C_(A)-C_((B/A))-C_(A);X-[-C_((B/A))-C_(A)]₂ and Y-[-C_((B/A))-C_(A)]₂, and the random blockC_((B/A)) may itself have been subdivided here into blocksC_((B1/A1))-C_((B2/A2))-C_((B3/A3)) . . . The random block is preferablycomposed of from 2 to 15 random sub-blocks, particularly preferably offrom 3 to 10 sub-blocks. The subdivision of the random block C_((B/A))into a large number of sub-blocks C_(Bn/An) gives the decisive advantagethat the sub-block C_((B/A)) block overall behaves as an almost perfectrandom polymer even if there is continuous change (gradient) in itsmakeup within a sub-block C_(Bn/An), as is difficult to avoid in anionicpolymerization under industrial conditions (see below). Clearly, onepossibility is to add less than the theoretical amount of potassiumalkoxide. Some proportion of the sub-blocks may be given a high dienefraction. This has the effect that the polymer retains a residual impactstrength, even below the glass transition temperature of the predominantC_((B/A)) blocks, and does not become completely brittle.

The property profile of the block copolymers of the invention is verysimilar to that of plasticized PVC, but they are prepared entirelywithout the use of low-molecular-weight plasticizers which can migrate.They resist crosslinking under the usual conditions of processing (from180 to 220° C.). The excellent resistance of the polymers of theinvention to crosslinking may be unambiguously proven by rheography. Theexperimental arrangement corresponds to that for MVR measurement. Therise in pressure as a function of time is recorded at a constant meltflow rate. Even after 20 minutes at 250° C., the polymers of theinvention show no rise in pressure and give a smooth extrudate, whereasfor a comparative specimen prepared in accordance with DE-A 44 20 952with tetrahydrofuran the pressure under the same conditions increases bya factor of three and the extrudate has the barbed-wire appearancetypically seen when crosslinking occurs.

The polymerization is carried out in two or more stages and in the caseof monofunctional initiation, for example, begins with preparing thehard block C_(A). A portion of the monomers is first placed in thereactor, and the polymerization is initiated by adding the initiator. Inorder to achieve a specified chain structure which can be calculatedfrom the amounts of monomer and initiator added, it is advisable to takethe process to high conversion (above 99%) before the second monomer isadded, but this is not an essential requirement.

The sequence of monomer addition depends on the block structureselected. In the case of monofunctional initiation, the vinylaromaticcompound is an initial charge, for example, or is directly metered in. Acyclohexane solution of the potassium alkoxide is then added. Diene andvinylaromatic should then be added simultaneously, if at all possible.The addition may take place in two or more portions. The ratio betweenthe amount of diene and that of vinylaromatic compound, and also theconcentration of the potassium salt and the temperature, bring about therandom structure and determine the makeup of the block C_((B/A)). Theproportion by weight of the diene, relative to the entire weightincluding vinylaromatic compound, is from 25 to 70%. Block C_(A) maythen be polymerized on by adding the vinylaromatic. As an alternative,polymer blocks required may also be bonded to one another by a couplingreaction. In the case of bifunctional initiation, the C_((B/A)) block isbuilt up first, followed by the C_(A) block.

Work-up follows by the usual processes. Procedures which are advisablehere are to work in a mixing vessel and to use an alcohol, such asisopropanol, to terminate the polymerization, to use CO₂/water in aconventional manner for making the mixture weakly acidic prior towork-up, to stabilize the polymer with an oxidation inhibitor and afree-radical scavenger (commercially available products, such astrisnonylphenyl phosphite (TNPP) or α-tocopherol (vitamin E) and/orproducts obtainable with the trade name Irganox 1076 or Irganox 3052) toremove the solvent by the usual processes; and extrude and pelletize.

As component (D) the thermoplastic molding compositions of the inventionmay comprise from 0 to 300% by weight, based on the entirety of (A), (B)and (C), preferably from 0 to 200% by weight, of at least onepolycarbonate.

Examples of suitable polycarbonates are those based on diphenols of theformula II

where Z is a single bond, C₁-C₃-alkylene, C₂-C₃-alkylidene,C₃-C₆-cycloalkylidene, —S— or —SO₂.

Preferred diphenols of the formula II are, for example,4,4′-dihydroxydiphenyl, 2,2-bis(4-hydroxyphenyl)-propane,2,4-bis(4-hydroxyphenyl)-2-methylbutane and1,1-bis(4-hydroxyphenyl)cyclohexane. Particular preference is given to2,2-bis(4-hydroxyphenyl)propane and 1,1-bis(4-hydroxyphenyl)cyclohexane.

Both homopolycarbonates and copolycarbonates are suitable as component(D); besides bisphenol A homopolymer, preference is also given tocopolycarbonates of bisphenol A.

The polycarbonates which are suitable may be branched in a known manner,preferably by the incorporation of from 0.05 to 2.0 mol %, based on thetotal of the diphenols employed, of at least trifunctional compounds,for example those having three or more phenolic OH groups.

The polycarbonates which are suitable as component (D) may, furthermore,be aromatically mono- to trisubstituted with halogen, preferably withchlorine and/or bromine, but particular preference is given tohalogen-free compounds.

Polycarbonates which have proven particularly suitable are those havingrelative viscosities η_(rel) of from 1.10 to 1.50, in particular from1.25 to 1.40. This corresponds to average molecular weights M_(w)(weight average) of from 10000 to 200000, preferably from 20000 to80000.

The diphenols of formula II are known per se or can be prepared by knownprocesses.

The polycarbonates can be prepared, for example, by reaction of thediphenols with phosgene in the interfacial process or with phosgene inthe homogeneous phase process (the pyridine process), the molecularweight to be set in each case being achieved in a known manner using anappropriate amount of known chain terminators. (For polycarbonatescontaining polydiorganosiloxanes see for example DE-A 33 34 782.)

Suitable chain terminators are, for example, phenol, p-tert-butylphenoland long-chain alkylphenols, such as 4-(1,3-tetramethylbutyl)phenol asin DE-A 28 42 005 or monoalkylphenols or dialkylphenols with from 8 to20 carbon atoms in the alkyl substituents as in DE-A 35 06 472, such asp-nonylphenol, 3,5-di-tert-butylphenol, p-tert-octylphenol,p-dodecylphenol, 2-(3,5-dimethylheptyl)phenol and4-(3,5-dimethylheptyl)-phenol.

Other suitable polycarbonates are those based on hydroquinone orresorcinol.

Besides the components (A), (B), (C) and (D), the thermoplastic moldingcompositions may also contain additives and processing aids as componentE) in amounts of from 0 to 30% by weight, based on the total weight ofthe molding compositions. Additives and processing aids of this type arelubricants and demolding aids, pigments, dyes, flame retardants,antioxidants, light stabilizers, fillers and reinforcing agents offibrous or pulverulent character, and antistats, in the amounts usualfor these agents.

The molding compositions according to the invention can be prepared bymixing processes known per se, for example by melting in an extruder,Banbury mixer, compounder, roll mill or calender. The components may,however, also be mixed “cold” without melting, and the mixture in theform of a powder or consisting of granules melted and homogenized onlyat the processing stage.

The present invention therefore also provides a process for preparingthe thermoplastic molding compositions of the invention by mixing thecomponents by mixing processes known per se.

From the molding compositions it is possible to produce moldings of anytype, in particular films and flat articles. Films may be produced byextrusion, rolling, calendering and other processes known to the personskilled in the art. The molding compositions according to the inventionare shaped by heating and/or friction, by themselves or with addition ofplasticizing or other additives, to give a film which can be furtherprocessed or a flat article (sheet). An example of a method ofprocessing to give three-dimensional moldings of any type is injectionmolding.

The present invention therefore also provides the use of thethermoplastic molding compositions of the invention for producingmoldings, films or fibers. It also provides the moldings obtainableusing the thermoplastic molding compositions.

The thermoplastic molding compositions of the invention have betterflowability than comparable molding compositions together with betterdemoldability and thermoformability and show no reduction in coatabilityand are largely free from constituents which vaporize or exude.

If (A) is a butadiene rubber, the molding compositions have excellentpuncture resistance and notch impact strength. If (A) is an acrylaterubber, the very good impact strength is a particular feature whichshould be highlighted.

They are suitable for producing films, moldings (especially sheets) andfibers, with excellent capability for further processing bythermoforming, and also for producing injection moldings, especially forfast processing with short cycle times.

The molding compositions of the invention are suitable for use inelectrical devices, such as kitchen machinery, shavers, telephones,vacuum cleaners, monitor casings, keyboards, electric lawnmowers, toyrailroads, washing machines, dishwashers and refrigerators.

The molding compositions of the invention are also suitable forproducing automotive parts. An example of their use is in automotiveinteriors, in center consoles, door side panels, tachometer housings,ventilator nozzles, push buttons and switches. They are also suitablefor automotive exterior applications, such as wheel caps, exteriormirrors (pigmented, painted or electroplated), electroplated emblems,radiator grilles and spoilers.

The molding compositions of the invention are also suitable for toys,profile extrusion, pipe extrusion, sheet extrusion, double- andmultilayer extrusion and housing parts.

EXAMPLES

The following constituents were prepared (all % data are % by weight)

A: Preparation of Components A

The median particle size mentioned in the description of component (A)is the ponderal median of the particle sizes.

The median diameter corresponds to the d₅₀, according to which 50% byweight of all particles have a smaller, and 50% by weight a larger,diameter than the diameter corresponding to the d₅₀. In order tocharacterize the width of the particle size distribution, the d₅₀ andthe d₉₀ are often stated in addition to the d₅₀. 10% by weight of allparticles are smaller, and 90% by weight are larger, than the d₉₀diameter. Analogously, 90% by weight of all particles have a smaller,and 10% by weight a larger, diameter than the diameter corresponding tothe d₉₀. The quotient Q=(d₉₀−d₁₀)/d₅₀ is a measure of the width of theparticle size distribution. The smaller Q is, the narrower is thedistribution.

A1: Preparation of a Component A-I:

A) Preparation of a Graft Base A-I-1:

The preparation of the respective acrylate-based graft base((a₁₁₁)+(a₁₁₂)) was carried out according to the following generalspecification:

160 g of a mixture of 98% of butyl acrylate and 2% ofdihydrodicyclopentadienyl acrylate (DCPA) were heated to 60° C., withstirring, in 1500 g of water, with addition of 5 g of the sodium salt ofa C₁₂-C₁₈-paraffinsulfonic acid, 3 g of potassium peroxodisulfate, 3 gof sodium bicarbonate and 1.5 g of sodium pyrophosphate. 10 minutesafter the initiation of the polymerization, a further 840 g of butylacrylate were added over 3 hours. After monomer addition had ended, theemulsion was held at 60° C. for a further hour.

b) Preparation of a Particulate Graft Polymer A-I:

2100 g of the emulsion prepared according to specification a) were mixedwith 1150 g of water and 2.7 g of potassium peroxodisulfate and heatedto 65° C., with stirring. After the reaction temperature was reached,560 g of styrene/acrylonitrile in a ratio of 75:25 were added over 3hours. When the addition was complete, the emulsion was held at 65° C.for a further 2 hours. The graft polymer was precipitated from theemulsion using calcium chloride solution at 95° C., washed with water,and dried in a stream of warm air.

A2: Preparation of a Component A-II:

a) Preparation of a Graft Base A-II-1

The preparation of the respective butadiene-based graft base((a₁₂₁)+(a₁₂₂)) was carried out according to the followingspecification:

A polybutadiene latex is prepared by polymerization at 65° C. of 600 gof butadiene in the presence of 6 g of tert-dodecyl mercaptan, 7 g ofsodium C₁₄-alkylsulfonate as emulsifier, 2 g of potassiumperoxodisulfate and 2 g of sodium pyrophosphate in 800 ml of water. Theconversion if 98%. The resultant latex has a median particle size of 100nm. This latex is agglomerated by adding 25 g of an emulsion of acopolymer of 96 parts of ethyl acrylate and 4 parts of methacrylamide,with a solids content of 10% by weight, giving a polybutadiene latexwith a median particle size of 350 nm.

b) Preparation of a Particulate Graft Polymer A-II:

After addition of 400 g of water, 4 g of sodium C₁₄-alkylsulfonate and 2g of potassium peroxodisulfate to the graft base prepared tospecification a, 400 g of a mixture of styrene and acrylonitrile (3:1)are introduced over a period of 4 hours. The polymerization takes placeat 75° C. while the mixture is stirred. The conversion, based onstyrene-acrylonitrile, is practically quantitative. The resultant graftrubber dispersion is precipitated by means of magnesium sulfatesolution, and the isolated graft copolymer is washed with distilledwater and dried.

A3: Preparation of a Component A-III:

a) Preparation of a Graft Base A-III-1

4312 g of butadiene are polymerized at 65° C. in the presence of 43 g oftert-dodecyl mercaptan, 31.1 g of potassium salt of C₁₂-C₂₀ fatty acids,8.2 g of potassium persulfate, 14.7 g of sodium hydrogencarbonate and5840 g of water to give a polybutadiene latex. The procedure is asdescribed in EP-A 0 062 901. The conversion is 96%, and the medianparticle size is from 80 to 120 nm.

To agglomerate the latex, 3500 g of the resultant dispersion are mixedat 65° C. with 287 g of a dispersion (solids content 10% by weight) madefrom 96% by weight of ethyl acrylate and 4% by weight of methacrylamide.

b) Preparation of a Particulate Graft Polymer A-III:

930 g of water, 13 g of potassium salt of C₁₂-C₂₀ fatty acids and 1.7 gpotassium peroxodisulfate are added to the resultant agglomerated latex.897 g of a mixture of styrene and acrylonitrile (80:20% by weight) arethen added within a period of 4 hours. The d₅₀ of the particle sizedistribution of the resultant graft dispersion is from 150 to 350 nm.

A4: Preparation of Componenet A-IV

a) Preparation of a Graft Base A-IV-1

4 parts of vinyl methyl ether, 15 parts of butyl acrylate and 15 partsof butadiene are heated to 65° C., with stirring, in 150 parts of waterwith addition of 1.2 parts of the sodium salt of a paraffinsulfonic acid(C₁₂-C₁₈), 0.3 part of potassium persulfate, 0.3 part of sodiumbicarbonate and 0.15 part of sodium pyrophosphate. Once thepolymerization has begun, a mixture made from 43 parts of butyl acrylateand 23 parts of butadiene is added within a period of 5 h. Once all ofthe monomers have been added, the polymerization mixture held at 65° C.for a further 2 hours. This gives an aqueous dispersion of about 40%strength.

b) Preparation of a Particulate Graft Polymer A-IV

250 parts of the first-stage dispersion (graft base) (A-IV-1) are mixedwith 60 parts of a mixture made from styrene and acrylonitrile andsufficient water to form a 40% strength dispersion, and polymerized at70° C., with stirring.

0.2% of potassium persulfate and 0.3% of lauroyl peroxide—in each casebased on the monomer—are added as polymerization initiator and dissolvedin the mixture of the monomers.

B: Preparation of Component B

The preparation of component B was carried out by the continuoussolution polymerization process as described in Kunststoff-Handbuch, Ed.R. Vieweg and G. Daumiller, Vol. V “Polystyrol”, Carl-Hanser-Verlag,Munich 1969, pp. 122-124.

B1: Component B-I:

A copolymer of styrene and acrylonitrile having 35% by weight ofacrylonitrile (AN) and a viscosity number of 60 ml/g, measured as 0.5%strength solution in dimethylformamide according to DIN 53726.

B2: Component B-II:

A copolymer of styrene and acrylonitrile having 25% by weight ofacrylonitrile and a viscosity number of 64 ml/g, measured as 0.5%strength solution in dimethylformamide according to DIN 53726.

B3: Component B-III:

As component B2, but with a viscosity number of 80 ml/g, measured as0.5% strength solution in dimethylformamide according to DIN 53726.

B4: Component B-IV:

As B1, but with a viscosity number of 80 ml/g, measured as 0.5% strengthsolution in dimethylformamide according to DIN 53726.

C: Preparation of Component C

To prepare component C, a 50 liter stainless steel autoclave equippedwith a cross-blade agitator and simultaneous heating and coolingfacilities was prepared by flushing with nitrogen and scalding with asolution of sec-butyllithium and 1,1-diphenylethylene in a molar ratioof 1:1 in cyclohexane, and drying. 22.8 l of cyclohexane were thencharged, and the amounts given in Table 1 of initiator, monomers andpotassium alkoxide were added. The polymerization time is also given, asis the initial temperature T_(I) and final temperature T_(F), themonomer feed time always being short in relation to the polymerizationtime.

The temperature of the reaction mixture was controlled by heating orcooling the reactor jacket. Once the reaction had ended (monomersconsumed) ethyl formate was titrated in until the mixture was colorless,and the mixture was acidified with a 1.5-fold excess of formic acid.Finally, 34 g of a commercially available stabilizer (®Irganox 3052;Ciba-Geigy, Basle) and 82 g of trisnonylphenyl phosphite were added.

The solution was worked up in a vented extruder (three vents, forwardand back venting) at 200° C. The resultant granules were used to preparethe molding composition.

TABLE 1 Polymerization and analysis of an S-SB-S block copolymer(component C) Buta- Buta- Buta- diene diene diene 1 [g] 2 [g] 3 [g]Styrene Styrene Styrene Styrene Styrene 1 [g] 2 [g] 3 [g] 4 [g] 5 [g]T_(I)/T_(F) K salt T_(I)/T_(F) T_(I)/T_(F) T_(I)/T_(F) T_(I)/T_(F) sec-[° C.] [mmol] [° C.] [° C.] [° C.] [° C.] buli Time Li:K Time Time TimeTime [mmol] [min] ratio [min] [min] [min] [min] 1638 2.36 1250 1250 12501638 87.3 40/68 1126 1126 1126 70/80  30 37:1 52/74 54/75 56/75  40  13 13  17 M_(n) [g/mol · 10^(−3]) T_(g,1) [° C.] M_(p) [g/mol · 10^(−3])M_(w) [g/mol · 10^(−3]) T_(g,2) [° C.] 136 000 −55 to −25 158 000 (deltaCp 68%) 163 000 60 to 100 (delta Cp 32%)

The average molar masses (in g/mol) of the polymer were determined bygel permeation chromatography (calibrated against polystyrene). M_(n)here means number average, M_(v) means viscosity average, and M_(w)means weight average.

The glass transition temperatures T_(g) were determined by DSC and werefrom −55 to −25° C. for the soft phase and from +60 to +100° C. for thehard phase.

The melt volume index MVI was determined at 200° C. with a load of 5 kgaccording to DIN 53 735, and was 8.5 ml/10 min.

Thermoplastic Molding Compositions

The molding compositions of the invention and the comparativecompositions were prepared at 250° C. and 200 rpm, with 10 kg/hthroughput, in a ZSK 30 extruder from Werner and Pfleiderer. The productwas cooled in a water bath, pelletized and injection molded on an ArburgAllrounder injection molding machine to give test specimens. Elongationat break was tested according to DIN 53504.

The results for the first embodiment of the present invention are listedin Tables 2 and 3 below.

The results for the second embodiment of the invention are listed inTables 4 to 8 below.

TABLE 2 Mixture/ component Unit 1 2 3 4 5 A3 % 40 38 36 34 32 B3 % 60 5754 51 48 C % 0 5 10 15 20 MVR 220/10 cm³/ 3.6 4.7 6.1 8.9 13 10 minBreaking MPa 33 29 27 26 24 stress Yield % 3.1 3.3 3.2 3.3 3.4 stressCharpy kJ/m² no no no no no impact frac- frac- frac- frac- frac-strength ture ture ture ture ture 23° C. Charpy kJ/m² 32.8 34.9 40.443.9 47.1 notch impact strength 23° C. Charpy kJ/m² 17 9 10 8 5 notchimpact strength −30° C. Pene- 25 26 26 26 24 tration test Yellowing +32+25 +27 +27 +27 after exposure to light for 16 h Vicat ° C. 96.5 94 9185 80

TABLE 3 Mixture/ component Unit 11 12 13 14 15 A1 % 42 39.9 37.8 35.733.6 B4 % 58 55.1 52.2 49.3 46.4 C % 0 5 10 15 20 MVR 220/10 cm³/10 min4.7 4.9 7.9 8.9 13.3 Breaking MPa 35 34 31 28 28 stress Stress % 3.5 3.43.5 3.5 3.6 yield % Charpy kJ/m² 46.8 48.4 49.7 28.3 22.3 notch impactstrength 23° C. Charpy kJ/m² 2.3 2.3 2 1.8 1.8 notch impact strength−30° C. Pene- 25 25 11 9 9 tration test MT 220° Vicat ° C. ° C. 91.590.5 86.2 79.3 73.4

The flowability of the molding compositions was determined on pellets,via the melt flow volume index MVR (melt volume ratio) at 220° C. with aload of 10 kp. The data given are the amounts in ml discharged through astandard die in 10 min.

Charpy impact strength was measured according to ISO 179/1 eU, ontensile specimens of dimension 4 mm.

Charpy notch impact strength was measured on test specimens ofdimensions 80×10×4 mm injection molded at 240° C. melt temperature/60°C. mold temperature with milled notch, testing according to ISO 179/1eA.

Puncture resistance was measured according to ISO 6603.

Heat resistance: determined according to DIN 53 460 as Vicat value,using test method A.

TABLE 4 ISO test Component specification Unit 1 2 3 4 5 6 7 A2 % 30 29.428.5 27 24 15 6 B1 % 70 68.6 66.5 63 56 35 17 C % 0 2 5 10 20 50 80 Meltvolume ratio (220° C./10 kg) 1133 cm³/10 min 16.3 16.9 18.7 23.1 34.273.9 74 Vicat softening point VST/B/50 306 ° C. 101.3 100.6 99.2 97.099.1 59.9 nm¹⁾ Charpy impact strength at 23° C. 179/leU kJ/m² 226 237276 296 nf²⁾ nf²⁾ nm¹⁾ Charpy impact strength at −30° C. 179/leU kJ/m²82.8 93.5 105 99.4 146 nf²⁾ nm¹⁾ Charpy notch impact strength at 23° C.179/leA kJ/m² 14.3 12.4 13.7 12.5 34 31 nm¹⁾ Charpy notch impactstrength at −30° C. 179/leA kJ/m² 5.4 4.6 4.5 4.1 3.8 2.7 — IZOD notchimpact strength at 23° C. 180/1A kJ/m² 18.4 13.8 14.8 IZOD notch impactstrength at −30° C. 180/1A kJ/m² 5.4 4.5 4.3 Elongation at yield stress527-2 % 2.9 2.9 2.9 2.9 2.9 2.5 8.4 Nominal elongation at break 527-2 %7.9 9.2 10.8 14.2 21.4 117 351 Modulus of elasticity in tension 527-2MPa 2390 2330 2245 2148 1745 1108 298 Flexural strength (max) 178 MPa74.9 72.9 69.4 63.6 47.3 26.7 — Yellowness 48.8 48.1 47.1 44.1 41.7 3422.4 ¹⁾nm: not measurable ²⁾nf: no fracture

TABLE 5 ISO test Component specification Unit 1 2 3 4 5 6 7 A3 % 30 29.428.5 27 24 15 6 B2 % 70 68.6 66.5 63 56 35 17 C % 0 2 5 10 20 50 80 Meltvolume 1133 cm³/10 min 17.2 19.8 21.5 26.1 36.5 72.8 nm¹⁾ ratio (220°C./10 kg) Vicat softening point VST/B/50 306 ° C. 96.3 95.5 94.3 90.683.2 nm¹⁾ nm¹⁾ Charpy impact strength at 23° C. 179/leU kJ/m² 157 208221 269 nf²⁾ nf²⁾ nm¹⁾ Charpy impact strength at −30° C. 179/leU kJ/m²101 119 121 124 138 nf²⁾ nm¹⁾ Charpy notch impact strength at 23° C.179/leA kJ/m² 22.9 27.1 31.3 37.1 34.4 55.3 nm¹⁾ Charpy notch impactstrength at −30° C. 179/leA kJ/m² 7.5 6.8 6.2 5.2 3.6 3.3 nm¹⁾ IZODnotch impact strength at 23° C. 180/1A kJ/m² 17.6 23.3 28.7 — — — — IZODnotch impact strength at −30° C. 180/1A kJ/m² 7.6 7.3 6.7 — — — —Elongation at yield stress 527-2 % 2.7 2.8 2.9 2.9 2.9 3.2 10.9 Nominalelongation at break 527-2 % 5.2 5.7 8.7 11.6 21.4 122 389 Modulus ofelasticity in tension 527-2 MPa 2205 2143 2063 1946 1746 986 251Flexural strength (max) 178 MPa 65.9 63.8 60.9 55.6 47.6 22.5 —Yellowness 27.3 26.0 24.4 23.3 21.5 15.5 nm¹⁾ ¹⁾nm: not measurable ²⁾nf:no fracture

TABLE 6 ISO test Component specification Unit 1 2 3 4 5 A3 % 30 29.428.5 27 24 B3 % 70 68.6 66.5 63 56 C % 0 2 5 10 20 Melt volume ratio(220° C./10 kg) 1133 cm³/10 min 6.4 7.2 8.4 11.4 18.8 Vicat softeningpoint VST/B/50 306 ° C. 99.9 99.3 98.1 94.4 80 Charpy impact strength at23° C. 179/leU kJ/m² 183 232 221 269 nf²⁾ Charpy impact Strength at −30°C. 179/leU kJ/m² 110 107 92.4 137 154 Charpy notch impact strength at23° C. 179/leA kJ/m² 16.9 21.9 27.6 35.6 30.2 Charpy notch impactstrength at −30° C. 179/leA kJ/m² 6.9 6.7 5.9 4.9 2.6 IZOD notch impactstrength at 23° C. 180/1A kJ/m² 14.1 17.2 22.5 — — IZOD notch impactstrength at −30° C. 180/1A kJ/m² 6.9 6.4 5.5 — — Elongation at yieldstress 527-2 % 3.1 3.1 3.1 3.0 3.0 Nominal Elongation at break 527-2 %4.9 5.7 8.2 12.8 24.9 Modulus of Elasticity in tension 527-2 MPa 22902240 2180 2050 1760 Flexural Strength (max) 178 MPa 73.0 70.9 67.1 60.050.5 Yellowness 27.5 26.5 25.0 23.8 21.6 ²⁾nf: no fracture

TABLE 7 ISO test Component specification Unit 1 2 3 4 5 A4 % 30 29.428.5 27 24 B4 % 70 68.6 66.5 63 56 C % 0 2 5 10 20 Melt volume ratio(220° C./10 kg) 1133 cm³/10 min 2.7 2.7 3.4 4.8 11.6 Vicat softeningpoint VST/B/50 306 ° C. 100.3 99.6 97.8 91.2 75 Charpy impact strengthat 23° C. 179/leU kJ/m² 198 236 nd¹⁾ nd¹⁾ nd¹⁾ Charpy impact strength at−30° C. 179/leU kJ/m² 85.5 118 107 135 61 Charpy notch impact strengthat 23° C. 179/leA kJ/m² 9.3 10.7 12.2 17.5 29.6 Charpy notch impactstrength at −30° C. 179/leA kJ/m² 2.8 3.1 2.6 2.5 1.8 IZOD notch impactstrength at 23° C. 180/1A kJ/m² 8.8 9.6 8.5 — — IZOD notch impactstrength at −30° C. 180/1A kJ/m² 3.5 3.8 3.2 — — Elongation at yieldstress 527-2 % 3.7 3.7 3.7 3.6 3.7 Nominal Elongation at break 527-2 %12.7 14 15 20.6 42 Modulus of Elasticity in tension 527-2 MPa 2180 21202042 1920 1640 Flexural strength (max) 178 MPa 70.4 66.7 63.3 59.2 46.8Yellowness 42.8 43.7 42.7 43.1 39.4 ¹⁾not determined

The results show that, even if the amounts of component C are small,there is a rise in impact strength, without (if the amounts are small)any substantial impairment of the other properties of the moldingcompositions.

TABLE 8 Component 1 2 A3 [%]  40 39.2 B3 [%]  60 58.8 C [%] — 2 IZODnotch impact 170 350 strength at 23° C.¹⁾ [kJ/m²] IZOD notch impact 350350 strength at 23° C.²⁾ [kJ/m²] ¹⁾IZOD notch impact strengthperpendicular to extrusion direction ²⁾IZOD notch impact strengthparallel to extrusion direction

A comparison of the IZOD notch impact strengths between moldingcompositions without addition of component C (1) and those with additionof component C (2) shows a marked improvement in IZOD notch impactstrength perpendicular to the extrusion direction with addition ofcomponent C.

We claim:
 1. A thermoplastic molding composition comprising (A) from 5to 98% by weight, based on the total weight of the molding composition,of an elastomeric graft copolymer built up from (a₁) from 30 to 90% byweight, based on (A), of a graft base with a glass transitiontemperature (T_(g)) below −10° C. made from (a₁₁) an at least partiallycrosslinked acrylate polymer formed from (a₁₁₁) from 50 to 99.9% byweight, based on (a₁₁), of at least one C₁-C₁₀-alkyl acrylate, (a₁₁₂)from 0.1 to 5% by weight, based on (a₁₁), of at least one polyfunctionalcrosslinking monomer and (a₁₁₃) from 0 to 49.9% by weight, based on(a₁₁), of at least one further monomer which is copolymerizable with(a₁₁₁) selected from the group consisting of the vinyl C₁-C₈-alkylethers, butadiene, isoprene, styrene, acrylonitrile andmethacrylonitrile, and/or methyl methacrylate and/or (a₁₂) a dienepolymer built up from (a₁₂₁) from 60 to 100% by weight, based on (a₁₂),of at least one diene and (a₁₂₂) from 0 to 40% by weight, based on(a₁₂), of further copolymerizable monomers selected from the groupconsisting of the C₁-C₁₀-alkyl acrylates, vinyl C₁-C₈-alkyl ethers,butadine, isoprene, styrene, acrylonitrile and methacrylonitrile, and/ormethyl methacrylate, (a₂)from 10 to 70% by weight, based on (A), of agraft with a (T_(g)) above 50° C., grafted onto the graft base an builtup from (a₂₁) from 50 to 95% by weight, based on (a₂), of at least onevinylaromatic monomer, (a₂₂) from 5 to 50% by weight, based on (a₂), ofat least one polar, copolymerizable comonomer selected from the groupconsisting of acrylonitrile, methacrylonitrile, C₁-C₄-alkyl(meth)acrylates, maleic anhydride and maleimides, and (meth)acrylamide,and/or vinyl C₁-C₈-alkyl ethers, or a mixture of these, (B) from 1 to90% by weight, based on the total weight of the molding composition, ofa copolymer composed of (b₁) from 50 to 99% by weight, based on (B), ofat least one vinylaromatic monomer and (b₂) from 1 to 50% by weight,based on (B), of monomers as described for (a₂₂), (C) from 1 to 70% byweight, based on (A), (B), (C) and optionally (D), of a block copolymercomposed of at least one block C_(A) forming a hard phase and havingcopolymerized units of a vinylaromatic monomer and at least oneelastomeric block C_((B/A)) forming a soft phase and havingcopolymerized units of a vinylaromatic monomer, and also of a diene,where the glass transition temperature (T_(g)) of the block C_(A) isabove 25° C. and that of the block C_((B/A)) is below 25° C., and theselected phase-volume ratio of block C_(A) to block C_((B/A)) is suchthat the proportion of the hard phase in the entire block copolymer isfrom 1 to 40% by volume and the proportion by weight of the diene in theentire block copolymer is less than 50% by weight, where the proportionof 1,2-linkages in copolymerized diene units, based on the total of 1,2-and 1,4-cis/trans linkages of the copolymerized diene units, is below15%, and (D) from 0 to 300% by weight, based on the weight of components(A) to (C), of a polycarbonate, (E) from 0 to 30% by weight, based onthe total weight of the molding composition, of conventional additivesand processing aids.
 2. A thermoplastic molding composition as claimedin claim 1, where a graft copolymer with a graft base (a₁₂) is used ascomponent (A).
 3. A thermoplastic molding composition as claimed inclaim 1, wherein the glass transition temperature T_(g) of the blockC_(A) in component is above 50° C. and that of the block C_((B/A)) isbelow 5° C.
 4. A thermoplastic molding composition as claimed in claim1, wherein the vinylaromatic monomer in component (C) has been selectedfrom the group consisting of styrene, α-methylstyrene, vinyltoluene,1,1-diphenylethylene and mixtures of these compounds, and the diene hasbeen selected from the group consisting of butadiene, isoprene,piperylene, 1-phenylbutadiene and mixtures of these compounds.
 5. Athermoplastic molding composition as claimed in claim 1, in whichcomponent (C) has one of the formulae 1 to 11:(C_(A)-C_((B/A)))_(n)  (1) (C_(A)-C_((B/A)))_(n)-C_(A)  (2)C_((B/A))-(C_(A)-C_((B/A)))_(n)  (3) X-[(C_(A)-C(B/A))_(n)]_(m+1)  (4)X-[(C_((B/A))-C_(A))_(n)]_(m+1)  (5)X-[(C_(A)-C_((B/A)))_(n)-C_(A)]_(m+1)  (6)X-[(C_((B/A))-C_(A))_(n)-C_((B/A))]_(m+1)  (7)Y-[(C_(A)-C_((B/A)))_(n)]_(m+1)  (8)Y-[(C_((B/A))-C_(A))_(n)]_(m+1)  (9)Y-[(C_(A)-C_((B/A)))_(n)-C_(A)]_(m+1)  (10)Y-[(C_((B/A))-C_(A))_(n)-C_((B/A))]_(m+1)  (11) where C_(A) is thevinylaromatic block and C_((B/A)) is the soft phase, i.e. the blockbuilt up randomly from diene units and from vinylaromatic units, X isthe residue of an n-functional initiator, Y is the residue of anm-functional coupling agent, and m and n are natural numbers from 1 to10.
 6. A process for preparing thermoplastic compositions as claimed inclaim 1, which comprises mixing the components (A) to (C) and optionally(D) and (E).
 7. A method of producing films comprising the step ofextrusion, rolling, calandering a thermoplastic molding composition asclaimed in claim
 1. 8. A method of producing three-dimensional moldingscomprising the step of injection molding a thermoplastic moldingcompositions as claimed in claim
 1. 9. The thermoplastic moldingcomposition defined in claim 1, wherein the proportion of 1,2-linkagesin the copolymerized diene units, based on the total of 1,2- and1,4-cis/trans linkages of the copolymerized diene units, is below 12%.10. The thermoplastic molding composition defined in claim 9, whereinthe proportion of 1,2-linkages in the copolymerized diene units, basedon the total of 1,2- and 1,4-cis/trans linkages of the copolymerizeddiene units, is of from 9 to 11%.
 11. A thermoplastic moldingcomposition comprising (A) from 5 to 98% by weight, based on the totalweight of the molding composition, of at least one elastomeric graftcopolymer built up from (a₁)from 30 to 90% by weight, based on (A), of agraft base with a glass transition temperature (T_(g)) below −10° C.made from (a₁₁) an at least partially crosslinked acrylate polymerformed from (a₁₁₁₁) from 50 to 99.9% by weight, based on (a₁₁), of atleast one C₁-C₁₀-alkyl acrylate, (a₁₁₂) from 0.1 to 5% by weight, basedon (a₁₁), of at least one polyfunctional crosslinking monomer and (a₁₁₃)from 0 to 49.9% by weight, based on (a₁₁), of a least one furthermonomer which is copolymerizable with (a₁₁₁) selected from the groupconsisting of the vinyl C₁-C₈-alkyl ethers, butadiene, isoprene,styrene, acrylonitrile and methacrylonitrile, and/or methyl methacrylateand/or (a₁₂) a diene polymer built up from (a₁₂₁) from 60 to 100% byweight, based on (a₁₂), of at least one diene and (a₁₂₂) from 0 to 40%by weight, based on (a₁₂), of further copolymerizable monomers selectedfrom the group consisting of the C₁-C₁₀-alkyl acrylates, vinylC₁-C₈-alkyl ethers, butadiene, isoprene, styrene, acrylonitrile andmethacrylonitrile, and/or methyl methacrylate, (a₂) from 10 to 70% byweight, based on (A), of a graft with a glass transition temperature(T_(g)) above 50° C., grafted onto the graft base and built up from(a₂₁) from 65 to 95% by weight, based on (a₂), of at least onevinylaromatic monomer, (a₂₂) from 5 to 35% by weight, based on (a₂), ofat least one polar, copolymerizable comonomer selected from the groupconsisting of acrylonitrile, methacrylonitrile, C₁-C₄-alkyl(meth)acrylates, maleic anhydride and maleimides, and (meth)acrylamide,and/or vinyl C₁-C₈-alkyl ethers, or a mixture of these, (B) from 1 to90% by weight, based on the total weight of the molding composition, ofa copolymer composed of (b₁) from 69 to 81% by weight, based on (B), ofat least one vinylaromatic monomer and (b₂) from 19 to 31% by weight,based on (B), of monomers as described for (a₂₂), (C) from 1 to 70% byweight, based on (A), (B), (C) and optionally (D) and (E), of anelastomeric block copolymer composed of at least one block C_(A) forminga hard phase and having copolymerized units of a vinylaromatic monomer,and at least one elastomeric block C_((B/A)) forming a soft phase andhaving copolymerised units of a vinylaromatic monomer, and also of adiene, where the glass transition temperature (T_(g)) of the block C_(A)is above 25° C. and that of the block C_((B/A)) is below 25° C., and theselected phase-volume ratio of block C_(A) to block C_((B/A)) is suchthat the proportion of the hard phase in the entire block copolymer isfrom 1 to 40% by volume and the proportion by weight of the diene in theentire block copolymer is less than 50% by weight, where the proportionof 1,2-linkages in copolymerized diene units, based on the total of 1,2-and 1,4-cis/trans linkages in the copolymerized diene units, is below15%, and (D) from 0 to 300% by weight, based on the weight of components(A) to (C), of a polycarbonate, of S-MA copolymers (styrenemaleic acidcopolymers), of S-imide-MA copolymers (styreneimide-maleic anhydridecopolymers), of S-imide-AN-MA copolymers(styrene-imide-acrylonitrilemaleic anhydride copolymers), of apolymethacrylamide, or of a polymethacrylate, and (E) from 0 to 30% byweight, based on the total weight of the molding composition, ofconventional additives and processing aids.
 12. A thermoplastic moldingcomposition as claimed in claim 11, wherein the proportion of component(C) is from 0.1 to 15% by weight, based on (A), (B), (C) and optionally(D) and (E).
 13. A thermoplastic molding composition as claimed in claim1, where a graft copolymer with a graft base (a₁₂) is used as component(A).
 14. A thermoplastic molding composition as claimed in claim 11,wherein the glass transition temperature T_(g) of the block C_(A) incomponent is above 50° C. and that of the block C_((B/A)) is below 5° C.15. A thermoplastic molding composition as claimed in claim 11, whereinthe vinyl aromatic monomer in component (C) has been selected from thegroup consisting of styrene, α-methylstyrene, vinyltoluene,1,1-diphenylethylene and mixtures of these compounds, and the diene hasbeen selected from the group consisting of butadiene, isoprene,piperylene, 1-phenylbutadiene and mixtures of these compounds.
 16. Athermoplastic molding composition as claimed in claim 11, in whichcomponent (C) has one of the formulae 1 to 11:(C_(A)-C_((B/A)))_(n)  (1) (C_(A)-C_((B/A)))_(n)-C_(A)  (2)C_((B/A))-(C_(A)-C_((B/A)))_(n)  (3)X-[(C_(A)-C_((B/A)))_(n)]_(m+1)  (4)X-[(C_((B/A))-C_(A))_(n)]_(m+1)  (5)X-[(C_(A)-C_((B/A)))_(n)-C_(A)]_(m+1)  (6)X-[(C_((B/A))-C_(A))_(n)-C_((B/A))]_(m+1)  (7)Y-[(C_(A)-C_((B/A)))_(n)]_(m+1)  (8)Y-[(C_((B/A))-C_(A))_(n)]_(m+1)  (9)Y-[(C_(A)-C_((B/A)))_(n)-C_(A)]_(m+1)  (10)Y-[(C_((B/A))-C_(A))_(n)-C_((B/A))]_(m+1)  (11) where C_(A) is the vinylaromatic block and C_((B/A)) is the soft phase, i.e. the block built uprandomly from diene units and from vinylaromatic units, X is the residueof an n-functional initiator, Y is the residue of an m-functionalcoupling agent, and m and n are natural numbers from 1 to
 10. 17. Aprocess for preparing thermoplastic molding compositions as claimed inclaim 11, which comprises mixing the components (A) to (C) andoptionally (D) and (E).
 18. A method of producing films comprising thestep of extrusion, rolling, calandering a thermoplastic moldingcomposition as claimed in claim
 11. 19. A method of producingthree-dimensional moldings comprising the step of injection molding athermoplastic molding as claimed in claim
 11. 20. The thermoplasticmolding composition defined in claim 11, wherein the proportion of1,2-linkages in the copolymerized diene units, based on the total of1,2- and 1,4-cis/trans linkages of the copolymerized diene units, isbelow 12%.
 21. The thermoplastic molding composition defined in claim20, wherein the proportion of 1,2-linkages in the copolymerized dieneunits, based on the total of 1,2- and 1,4-cis/trans linkages of thecopolymerized diene units, is of from 9 to 11%.